Interpretive Handbook

Test
61823 :
Mucopolysaccharidosis VI, Known Mutation

Mucopolysaccharidosis type VI (MPS-VI), also known as Maroteaux-Lamy syndrome, is an autosomal recessive condition that is caused by mutations in the ARSB gene and is characterized by reduced or absent activity of the arylsulfatase B enzyme. This test screens for mutations in all 8 exons of the ARSB gene.

The clinical features and severity of symptoms of Maroteaux-Lamy are widely variable. Typically it is characterized by short stature, dysostosis multiplex, facial dysmorphism, stiff joints, hepatosplenomegaly, corneal clouding, cardiac defects, and usually normal intelligence. With a rapidly progressing form of MPS-VI, onset occurs before 2 to 3 years of age with death typically occurring in the second to third decade. With a slowly progressing form of MPS-VI, a diagnosis usually occurs after 5 years of age but may not occur until the second or third decade.

The recommended first-tier test for MPS-VI is biochemical testing that measures arylsulfatase B enzyme activity in fibroblasts (ARSB / Arylsulfatase B, Fibroblasts). Individuals with decreased or absent enzyme activity are more likely to have 2 identifiable mutations in the ARSB gene by molecular genetic testing. However, enzymatic testing is not reliable to detect carriers.

The identification of a disease-causing mutation in an affected family member is necessary before predictive testing for other family members can be offered. If a familial mutation has not been previously identified, order MPS6S / Mucopolysaccharidosis VI, Full Gene Analysis.

Analysis is performed only for the provided familial mutations. This assay does not rule out the presence of other mutations within this gene or within other genes that may be associated with metabolic disease.

We strongly recommend that patients undergoing predictive testing receive genetic counseling both prior to testing and after results are available.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Any error in the diagnosis or in the pedigree provided to us, including false paternity, could lead to erroneous interpretation of results.

A previous bone marrow transplant from an allogenic donor will interfere with testing. Call Mayo Medical Laboratories for instructions for testing patients who have received a bone marrow transplant.